One man's steps to a greener lifestyle.

Monthly Archives: August 2018

For more than a year now we’ve been building up our smart home capability. There are various ecosystems of such devices, but we’re using Apple HomeKit a decision initially motivated by the presence of multiple iPads in the home.

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My first step into smart home was to replace radiator valves with smart valves. Typically that results in replacing a temperature-only TRV with a smart valve with both a temperature set point and schedule. A schedule still operated within the central heating timer, but The schedule within the valve allows heating to be disabled in a particular room even though on elsewhere.

Applications for this include disabling lounge heating on weekday mornings, disabling the playroom heating after our daughter’s bedtime, not heating bedrooms during weekend daytimes etc..

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My second step was to add the ability to turn on the heating remotely so, instead of having schedules in both the central timer and the individual valves, the schedules exist only in the valves. Instead rules link the valves to the boiler so the boiler automatically runs from the first radiator valve on to the last radiator valve off.

Thus, instead of potentially needing to modify both a valve schedule and the schedule on the central timer to make a change, only instead a single change to the valve schedule is required. Similarly things like extending heating in the evening, to watch a late film for example, a simple Siri voice command to the radiator valve is enough rather than having to extend boiler hours too.

The hardware to achieve this is a standard smart socket, driving a relay which closes contacts across the correct terminals on the central heating wiring block alongside the boiler. The software to achieve this is two rules - a boiler on rule and a boiler off rule. The rules require a hub to which to run which initially was my iPad.

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My third step was to add an Apple TV unit as a hub to complement the iPad. This allows the heating rules to operate even when the iPad is not at home of has insufficient battery charge to act as a hub.

Extra capability from this additional hub allows control from remote locations, such as warming up the home if one will be home early or disabling vacation setting prior to starting a home-bound journey at the end of a vacation.

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My fourth step started a completely different non-heating theme. We’d had a few occasions where family members had left the house with windows open, so I started adding sensors on windows that were most likely to the left open - typically cloakrooms/bathrooms.

In this step we needed to use the Apple Home app, the Elgato Eve App, or Siri to check window status.

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My fifth step continued that different non-heating theme with the addition of our first smart bulb, now in a lightfitting near the burglar alarm control panel.

A series of rules combine both automated dusk-to-dawn white lighting and coloured lighting when any monitored window is left open.

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My sixth step continued the lighting theme with the addition of our second smart bulb, now in the outside light by the front door. This light had an integral dusk-to-dawn sensor but this failed leaving the light on continuously. Rather than replace the whole lamp I simply added a white smart bulb.

The existing rules were modified to add the new bulb to provide dusk-to-dawn white lighting.

This step was added August 15th, 2018.

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My seventh step returned to the heating theme with the addition of our first movement sensor (an Eve Motion). The purchase was prompted by a fellow member of an online community identifying that these were on sale by a well-known online retailer for under £30. I purchased it without a specific plan how I would use it, but soon identified an opportunity in the heating.

In the new scheme the lounge heating is extended to run later by modifying the schedule in the Eve Energies, but then the movement sensor is used to curtail the heating earlier if no movement has been detected in half hour intervals after 10:00 PM.

This step was added September 21st, 2018.

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My eight step remained with the heating theme with the addition of another Eve Thermo eTRV. I had bought the sensor a few months ago when Maplin were closing down, but had not yet used it. However it seemed better to use it than leave it lying literally on the shelf.

The chosen location was the downstairs cloakroom that had previously had a standard TRV where the radiator heated to the set point whenever any smart value demanded heat. This was the first time that I had a smart valve in the same room as a window sensor and it was interesting to see the Eve App automatically create two new scenes to pause and resume heating in the room while the window was open. I also used the valve in a way new to me - rather than utilise the internal schedule instead I switch its temperature set point when any other valve demands heat. I thus consider this valve my first 'slave' valve - simply operating from first 'master' valve on to last 'master' valve off.

This step was added October 1st, 2018.

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My ninth step was one of general robustness via the introduction of a second Eve Energy, this time used to support a periodic check of status my 'watchdog'.

The Eve Energy supports a review of status every 5 minutes allowing output states to be corrected if an earlier change of state was missed and failed to trigger a rule.

My tenth step was a further one of general robustness via the introduction of a second Apple TV used as a second hub.

This second Apple TV is placed in a room diagonally across the house from the original. The original TV is at the South West corner of the hose, which isn’t ideal for BLE coverage, but happens to be next to the TV in the lounge. While it can reach all the smart devices from th8s location, there are occasions when the signal is lost. The second location should improve robustness for the more distant devices as signals are relayed via the second hub to which whichever hub the system regards as the master at the time. The hubs themselves communicate with each other via WiFi and onwards to the devices by Bluetooth/BLE.

This step was added October 29th, 2018.

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My eleventh step was to introduce two WIFIPLUG smart plugs to control dishwasher and washing machine.

The WIFIPLUG units were selected in preference to my existing Eve Energy devices due to the availability of an API interface allowing my HEMS to interact with the smart plugs. This was described wet goods project.

This morning I see that the Greening Me blog has 1,222 subscribers. Hopefully that’s 1,222 people taking steps to make a difference, rather than 1,222 people about to spam me!

For those who also use Facebook there is also an associated Facebook page which I use to share when there’s new content here, or share Facebook or news items which I think may be of interest to readers of this blog. If you would like to see (and hopefully follow) our Facebook page then you can click here.

In the last few days I’ve reported our status on electricity generation from our solar panels and our gas consumption, so here comes some thoughts on electricity purchase from the grid.

Starting in late 2015 after the meter was changed to Economy 7, there’s a general downward trend from November 2015 to March 2016, before my car charger project kicks in maximising use of my own solar electricity to charge my car (when available) which causes a significant drop in purchased electricity between march and April 2016. That seasonal saving gradually drops through the autumn, although it’s interesting that by November 2016 we’re back on what seems to be a continuation of a downward trend from January to March 2016. Electricity purchased is also significantly lower than 2015 as we enter the second year.

The second significant change is the addition of the storage battery in December 2016. However from January to August 2017 (yellow) electricity purchased is significantly below the prior year (magenta) – potentially showing the benefit of the battery in saving electricity generated during the day to reduce consumption later in the day. This benefit largely disappears from September to December 2017, presumably because my increased vehicle mileage after my daughter started school is offsetting the prior savings.

2018 (orange) generally falls somewhere between 2016 and 2017 as it combines both the storage battery and the higher vehicle mileage throughout the year to date.

This chart shows our gas consumption by month and year since we moved here in August 2015 (the first full month shown is September 2015), Along the way several changes are marked which might be thought to influence gas consumption, although with natural variation month-to-month and year-by-year the effect of those changes isn’t dramatically obvious.

What is of course obvious is the dramatic difference in gas consumption between summer and winter as gas is our main means of space heating, and there’s no need for space heating in summer. Most homes would exhibit such a pattern. Ours is probably a bit more marked than many because of our water heating. Many homes with gas will use the gas for both space and water heating, but for us the gas water heating is the back-up not the primary water heating system. Our home is set up to divert surplus solar electricity from the PV panels to water heating during the day. Only in the evening is gas water heating enabled and then it does no heating if the water is up to temperature. The gas water heating thermostat is also set a few degrees colder than the immersion heater, so gas is separated from electric water heating by both time and temperature to prioritise electricity.

Previously I had just disabled the boiler in summer, but occasional dull days would leave my wife complaining about lack of hot water. The new arrangement with the boiler operating later and with a lower temperature set-point has avoided that and is robust as long as your hot water cylinder is big enough for your daily needs so you only need to fill it once with hot water which is then stored available for use until the next day.

Over time 3 changes are called out which should reduce gas consumption further:

In December 2015 we replaced the boiler, hot water cylinder and controls. The previous boiler had demonstrated that it was incapable of heating the whole home as we went into our first winter so a replacement was rapidly arranged. The new boiler is considerably more efficient which should reduce gas consumption for a given heat output, but it now heats the whole house, so that might counteract the improved efficiency.

In late 2016 we upgraded the loft insulation from 100 to 270 mm which should be worth £73 in gas per year according to our EPC. February, March and April 2017 do seem to show some benefit compared to 2016, but then there also variation in the weather year-to-year.

In May 2017 we started adding smart heating controls which has gradually expanded over the following months. The overall concept here is that most rooms now have smart radiator valves which are both thermostatic and contain their own schedule. The schedules allow rooms to be heated for fewer hours: for example lounge not heated on weekday mornings, playroom not heated after children’s bedtime etc.